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    Real Time Phong Shading
    (The Eurographics Association, 1990) Claussen, Ute; Richard Grimsdale and Arie Kaufman
    Nowadays, hardware support for Gouraud shading is state-of-the-art. Most hardware implementations of the Phong shading algorithm lack flexibility, for example are restricted in the number of light sources. In this paper, we will present a concept of shading processors that has been developed in a rendering system called PROOF. Two types of processors have been designed, one performing the normalization of vectors. The other one is designed for faster and cheaper shading. The capabilities of the processors are demonstrated.
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    PROOF: An Architecture for Rendering In Object Space
    (The Eurographics Association, 1988) Schneider, Bengt-Olaf; Claussen, Ute; A. A. M.Kuijk
    This paper gives a short introduction into the field of computer image generation in hardware. It discusses the two main approaches, namely partitioning in Image space and In object space. Based on the object space partitioning approach we have defined the PROOF architecture. PROOF is a system that aims at high performance and high quality rendering of raster images. high performance means that up to 30 pictures are generated in one second. The pictures are shaded and anti-allased, giving the images a high degree of realism. The architecture comprises tnree stages which are responsible for hidden surface removal, shading, and filtering respectively. The first of these stages a pipeline of object processors. Each of these processors stores and scan converts one obiect Furthermore, It interpolates the depth and the normal vector across the Object. Each object processor IS able to handle objects of a certain primitive type. The specialization of an object processor to a certain primitive type is encapsulated in a Single block called primitive processor. The Outout of the object processor pipeline is the input to a stage for shading. The illumination model employed takes In~o account both diffuse and specular reflections. The paper reviews Gouraud and Phong shading with regard to their suitability for a hardware implementation. The final stage of the PROOF system is formed by a stage for filtering the colours of those objects that contribute to a pixel. This done by constructing a subpixel mask and filtering across an area of 2x2 pixels. At the end. the paper briefly reports on the current state of the project.
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    Parallel Subpixel Scanconversion
    (The Eurographics Association, 1987) Claussen, Ute; Fons Kuijk and Wolfgang Strasser
    "IntroductionComputer graphics and its subsections image processing, image analysis and image generation are known to be a wide field for the application of parallel architectures. While in image processing and analysis the demand for ""real time"" computation is in the center of discussion, it becomes more and more important in the field of image generation, too. Some applications, like sequences of realistic appearing images raise highest demands on algorithm and architecture as well."
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    On Reducing the Phong Shading Method
    (Eurographics Association, 1989) Claussen, Ute
    Today, the shading method of Phong plays an important role in the design of realtime image generation systems. Often, the model has been used in combination with a color interpolation, suppressing a main property of this model, namely the visually acceptable rendering of highlights. Unfortunately, Phong’s algorithm demands a normalization, which is expensive to implement in hardware. We will present several shading methods which are reductions of the Phong algorithm. They will be compared both visually and theoretically. The alternatives are judged concerning their costs for a hardware implementation. The result is a hierarchy of shading methods that can be used to select the required cost-performance ratio for a given visualization task.